This review concluded that local anaesthetic given at the incision site before laparoscopic surgery reduced postoperative pain compared with placebo but not post-incisional anaesthetic infiltration; pre-emptive local anaesthetic given intraperitoneally reduced pain compared with both placebo and postoperative infiltration. The authors' conclusions reflect the evidence presented, but limitations in the evidence suggest that the findings should be interpreted cautiously.

Authors' objectives

To assess the effect of local anaesthesia administered before laparoscopic surgery (pre-emptive anaesthesia) on postoperative pain.

Searching

MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched with no language restrictions. Search terms were reported but search dates were not. Reference lists of retrieved articles and two major textbooks were scanned. To locate unpublished trials, two indexes of conference proceedings and ClinicalTrials.gov were searched.

Study selection

Randomised controlled trials (RCTs) or quasi-RCTs were eligible for the review. Trials had to compare pre-emptive local anaesthetic administration with post-incisional or postoperative administration or placebo in patients undergoing laparoscopic surgery. Pre-emptive anaesthesia could be administered by local, incisional or intraperitoneal infiltration. Trials had to report pain, quality of life, postoperative complications or length of hospital stay as an outcome.

Included trials recruited patients undergoing various different types of surgery; cholecystectomy and gynaecological procedures were the most common. Included patients generally had an American Society of Anesthesiology score of 1 or 2. Bupivacaine (0.1 to 0.5%) was the most commonly used anaesthetic, followed by ropivacaine (0.19 to 3.75%) and lidocaine (0.5 to 1%).

Two reviewers selected studies for the review. Disagreements were settled by consensus or reference to a third reviewer.

Assessment of study quality

Trial quality was assessed by two reviewers independently and was based on allocation concealment, blinding (patients, investigators and outcome assessors) and completeness of follow-up.

Data extraction

Mean differences between treatment groups were extracted or calculated for continuous outcomes. When trials reported the median and range, the mean and standard deviation were estimated by the method of Hozo et al. Data for different surgery types or local anaesthetics in the same trial were extracted separately. Attempts were made to contact investigators to obtain missing data.

Data extraction was performed by two reviewers using standardised forms.

Methods of synthesis

Data were pooled by meta-analysis using random-effects models. Pooled weighted mean differences (WMD) and 95% confidence intervals (CI) were calculated for continuous outcomes with the same unit of measurement; standardised mean differences were calculated for outcomes with different units of measurement. Statistical heterogeneity was assessed by the Breslow-Day test (p<0.1 being considered significant) and I2. Possible sources of heterogeneity were explored using a series of subgroup and sensitivity analyses related to differences in population, intervention, outcomes and methodological quality.

Overall quality of evidence for each outcome was assessed by the GRADE (Grades of Recommendation Assessment, Development and Evaluation) system.

Publication bias was assessed using funnel plots.

Results of the review

Twenty-six trials (with 2,546 participants) were included in the review; sample size ranged from 28 to 190 participants. Quality was described as generally good, although allocation concealment was unclear in many trials. No evidence of publication bias was found.

Heterogeneity was present for all analyses of VAS pain scores (I2 60% to 91%); in most cases it was not explained by the pre-specified subgroup and sensitivity analyses.

Authors' conclusions

Pre-emptive administration of local anaesthetic at the incision site reduced post-operative pain compared with placebo, but not when compared with post-incisional anaesthetic infiltration. Pre-emptive local anaesthetic given intraperitoneally reduced pain compared with both placebo and post-operative infiltration.

CRD commentary

The review question and inclusion criteria were clear. The search included a number of relevant databases and included some attempts to locate unpublished studies. There were no language restrictions, which minimised the risk of language bias. Publication bias was assessed and no evidence of significant bias was found. Appropriate methods were used to reduce reviewer errors or bias affecting the review process.

Quality of the included trials was assessed using appropriate criteria. Relevant details of included trials were presented. Trials were pooled by meta-analysis. Sources of heterogeneity were investigated, although unexplained heterogeneity was present in most analyses. This suggested that the use of meta-analysis may not have been appropriate. As noted by the authors, incomplete reporting meant that not all the included trials could be used in the meta-analyses. The authors also noted that the benefit of local analgesia, although statistically significant, was modest.

The authors' conclusions were in line with the evidence presented, but limitations in the evidence base (poor reporting and unexplained heterogeneity) suggest that the findings should be interpreted cautiously.

Implications of the review for practice and research

Practice: The authors stated that local analgesia should be used in laparoscopic surgery but the timing of administration is only significant for intraperitoneal administration.

Research: The authors stated that it would be useful to compare incision site and intraperitoneal administration and to determine whether giving both together produces an additive effect on pain.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.